Fatty acid and fatty acid derivatives (such as fatty acid methyl esters (FAME), fatty alcohols, fatty amines, etc.) are important precursors to manufacturing many consumer products, industrial chemicals and fuels. For example, fatty acids and fatty acid derivatives are used to make detergents, cleaners, plastics, paper, paints, lubricants, waxes, coatings and surfactants. They can also be used as flavor and fragrance agents. Currently, fatty acids and fatty acid derivatives are produced from oleochemical (plant and animal fats) or petrochemical sources. In general, the fatty acids derived from oleochemical sources have aliphatic chains with an even number of carbons, whereas fatty acids derived from petrochemical sources have aliphatic chains with an odd number of carbons.
Both oleochemical and petrochemical fatty acids have significant shortcomings. Most notably, the feedstocks used to produce such fatty acids generally include a mixture of fatty acids of varying carbon chain lengths and may include a wide range of chain lengths, as well as saturated and unsaturated fatty acids. FIG. 1 is a chart that illustrates the fatty acid carbon composition of various common oleochemical feedstocks. Many of the commercial applications for fatty acids and fatty acid derivatives, however, require a fatty acid precursor having greater specificity with respect to its aliphatic chain lengths. For example, C6-C10 fatty acids are used in the production of jet lubricants, C12-C14 fatty acids are used to make surfactants and detergents, and C16-C18 fatty acids are used for metal soap production. As a result, current fatty acid production methods require costly feedstock processing procedures, such as fractionation and distillation, in order to isolate the fatty acid components required for a given application. There are technical limits to the effectiveness of such processing procedures and their ability to isolate relatively high concentrations of fatty acids of isolated chain lengths.
Another short coming of oleochemical and petrochemical fatty acids is the wide fluctuation in the cost of the feedstocks. Oleochemical feedstock prices are extremely volatile and can significantly fluctuate from year to year and fluctuate among the various geographic regions. Since overall production costs are very sensitive to feedstock price, such volatility can significantly impact margins. Regarding petrochemical fatty acids, there is increasing acceptance that petroleum hydrocarbon supplies are decreasing, and as a result their costs are expected to continue to increase.
Finally, there is increasing concern regarding sustainability within the chemical industry, and there is a growing demand for chemicals produced from renewable resources. In fact, many chemical companies and their customers have implemented sustainability initiatives with a goal of replacing current chemicals such as petro-based chemicals with chemicals made from renewable sources. Such companies are seeking renewable chemicals that have minimal impact on product performance or characteristics, as well as minimal impact on downstream products and customers. There are even sustainability concerns within the oleochemical industry. Although many of the oleochemical fatty acids are derived from renewable resources, current industry practices do not manage the harvesting of these resources in a sustainable way. For example, there has been significant concern regarding deforestation in the production of palm oil, a primary source for oleochemical fatty acids.
In view of these shortcomings regarding petro-based and oleo-based fatty acids and fatty acid derivatives, interest has increased for developing and improving industrial microbial systems for production of chemicals and fuels using sustainable plant-based feedstocks. Such industrial microbial systems could completely or partially replace the use of petroleum hydrocarbons or oleochemicals for production of certain chemicals and products.
Numerous chemicals are produced through such microbial systems, ranging from antibiotic and anti-malarial pharmaceutical products to fine chemicals to fuels such as ethanol. However, there is still a commercial need for modified microorganisms that are adapted to produce fatty acids and fatty acid derived products, and in particular, fatty acid and fatty acid derived products that have a high concentration of a specific fatty acid chain length.